Systems and methods for distributed interferometric acoustic monitoring
First Claim
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1. A method for distributed acoustic detection or monitoring of activity, comprising:
- transmitting a monitoring signal through a fiber optic cable, wherein the monitoring signal comprises a pulse of a coherent beam of electromagnetic radiation where a coherence time of the coherent beam of electromagnetic radiation is equal to or longer than a time duration of the pulse, and wherein the fiber optic cable is disposed in a subterranean section of the Earth;
detecting coherent Rayleigh noise generated by the transmission of the coherent beam of radiation through the fiber optic;
processing the detected coherent Rayleigh noise to identify one or more acoustic occurrences in the subterranean section of the Earth; and
monitoring or detecting the activity using the identified one or more acoustic occurrences.
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Abstract
A method and system for acoustic monitoring using a fiber optic cable. The optical fiber is used as a distributed interferometer that may be used to monitor activity, such as activity with respect to a conduit, wellbore or reservoir. The distributed interferometric monitoring provides for accurate detection of acoustic occurrences along the fiber optic cable and these acoustic occurrences may include fluid flow in a pipeline or wellbore, processes taking place in a wellbore or pipeline, fracturing, gravel packing, production logging and/or the like.
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21 Claims
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1. A method for distributed acoustic detection or monitoring of activity, comprising:
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transmitting a monitoring signal through a fiber optic cable, wherein the monitoring signal comprises a pulse of a coherent beam of electromagnetic radiation where a coherence time of the coherent beam of electromagnetic radiation is equal to or longer than a time duration of the pulse, and wherein the fiber optic cable is disposed in a subterranean section of the Earth; detecting coherent Rayleigh noise generated by the transmission of the coherent beam of radiation through the fiber optic; processing the detected coherent Rayleigh noise to identify one or more acoustic occurrences in the subterranean section of the Earth; and monitoring or detecting the activity using the identified one or more acoustic occurrences. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A system for distributed acoustic detection or monitoring of activity, comprising:
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a fiber optic cable disposed in a subterranean section of the Earth; a source of coherent electromagnetic radiation coupled with the fiber optic cable and configured in use to inject a pulse of coherent electromagnetic radiation into the fiber optic cable, wherein a coherence time of the coherent beam of electromagnetic radiation is equal to or longer than a time duration of the pulse; a detector coupled with the fiber optic cable and configured to detect coherent Rayleigh noise generated in the fiber optic cable by the pulse of coherent electromagnetic radiation; and a processor in communication with the detector and configured to detect or monitor activity by processing the detected coherent Rayleigh noise. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21)
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Specification